Since the discovery of penicillin, pharmaceutical companies have produced a number of antibacterial agents to combat a wide variety of bacterial infections. In the past several years, there has been rapid emergence of bacterial resistance to several of these antibiotics. The multidrug resistance among these bacterial pathogens may also be due to mutation leading to more virulent clinical isolation. Perhaps the most disturbing occurrence has been the acquisition of resistance to vancomycin, an antibiotic generally regarded as the agent of last resort for serious Gram-positive infections.
This is true especially of some Gram-positive pathogen groups, such as staphylococci, pneumococci and enterococci (S. Ewig et al.; Antibiotika-Resistenz bei Erregem ambulant erworbener Atemwegsinfektionen (Antibiotic resistance in pathogens of outpatient-acquired respiratory tract infections); Chemother. J. 2002, 11, 12-26; F. Tenover; Development and spread of bacterial resistance to antimicrobial agents: an overview; Clin. Infect. Dis. 2001 Sep. 15, 33 Suppl. 3, 108-115) as well as Staphylococcus, Streptococcus, Mycobacterium, Enterococcus, Corynebacterium, Borrelia, Bacillus, Chlamydia, Mycoplasma, and the like.
A problem of equally large dimension is the increasing incidence of the more virulent, methicillin-resistant Staphylococcus aureas (MRSA) among clinical isolates found worldwide. As with vancomycin resistant organisms, many MRSA strains are resistant to most of the known antibiotics, but MRSA strains have remained sensitive to vancomycin. However, in view of the increasing reports of vancomycin resistant clinical isolates and growing problem of bacterial resistance, there is an urgent need for new molecular entities effective against the emerging and currently problematic Gram-positive organisms.
This growing multidrug resistance has recently rekindled interest in the search for new structural classes of antibiotics that inhibit or kill these bacteria.